INFLUENCE OF ADJUVANTS ON ROUNDUP (REGISTERED TRADEMARK) EFFECTIVENESS. INTERIM REPORT

Roundup (glyphosate) was evaluated at four rates alone and at three rates with 11 adjuvants for the control of bermudagrass along highways near Leona and Center, Texas, in May and June 1993. Over the 12-week rating period, bermudagrass injury averaged 6% higher on the pavement than on the shoulder. The highest ratings occurred 4 weeks after treatment (WAT). All herbicide rates were generally equally effective 2 WAT. The 7.0 L/ha (3 qt/A) rate was equally effective as the 9.4 L/ha (4 qt/A) rate and more effective than the 3.5 or 4.7 L/ha (1.5 or 2 qt/A) rates at 8 and 12 WAT. Averaged over four tests, adjuvants caused some small, but inconsistent increases in Roundup effect on bermudagrass. Roundup activity at 7.0 L/ha (3 qt/A) alone was only increased slightly by Raider-TG at 2 WAT. Roundup activity at 3.5 and 4.7 L/ha (1.5 and 2 qt/A) was increased slightly by several adjuvants 8 and 12 WAT. Adjuvants had little effect by 12 WAT.